The first solution looks good. I had no idea that wrapping a defn inside of let's would leave the function exposed. Interesting. Is it considered idiomatic though?
On May 30, 2:16 pm, Erik Söhnel <eriksoeh...@googlemail.com> wrote: > Hi, > > Not really mechanisms, but two Idioms will help you with your problem: > Either wrap the defn in a let: > > (let [U (gen-matrix [1 2 2 -2 -1 -2 2 2 3] 3 3) > A (gen-matrix [1 2 2 2 1 2 2 2 3] 3 3) > D (gen-matrix [-1 -2 -2 2 1 2 2 2 3] 3 3) > S (gen-vector [3 4 5])] > (letfn [(prims-from [m] [(mult m U) (mult m A) (mult m D)]) > (next-prims [l] (flatten (map prims-from l)))] > (defn primitives > "Generates pythagorean primitives. Will filter them against > pred if > given." > ([] (iterate next-prims [S])) > ([pred] (iterate #(filter pred (next-prims %)) [S]))))) > > or use a default value for pred: (constantly true) > > (defn primitives > "Generates pythagorean primitives. Will filter them against pred if > given." > ([] (primitives (constantly true))) > ([pred] > (let [U (gen-matrix [1 2 2 -2 -1 -2 2 2 3] 3 3) > A (gen-matrix [1 2 2 2 1 2 2 2 3] 3 3) > D (gen-matrix [-1 -2 -2 2 1 2 2 2 3] 3 3) > S (gen-vector [3 4 5])] > (letfn [(prims-from [m] [(mult m U) (mult m A) (mult m D)]) > (next-prims [l] (flatten (map prims-from l)))])) > (iterate #(filter pred (next-prims %)) [S]))) > > The former will evaluate the values only once when the file is loaded > and keep them around until your program dies and do not impose any > runtime overhead when you call the function, because all variables are > already initialized. > The latter one uses a default argument to pred. (constantly true) > returns a n-argument function wich returns true on every invokation. > > Erik -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
